A Persona-based Modeling for Contextual Requirements Genana Nunes - - PowerPoint PPT Presentation

A Persona-based Modeling for Contextual Requirements

Genaína Nunes Rodrigues1, Carlos Joel Tavares1, Naiara Watanabe1 Carina Alves2 Raian Ali3

1Department of Computer Science, University of Brasília, 2Department of Computer Science, Federal University of Pernambuco 3Department of Computer Science, Bournemouth University

genaina@unb.br

REFSQ 2018

March 20, 2018

Rodrigues et al. A Persona-based Modeling for Contextual Requirements 1

Introduction

“A persona is a fictional character that represents a group of users of a given system and renders the product development more effective and accommodative to diversity” [Cooper, 2004]. ...and can add a human-centred facet to RE practice

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A Persona Example

Figure : The characterisation of persona Mary Collins.

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Introduction

Goal models (GM) provide the goals for which the system should be designed and a set of ways to reach those goals in prescriptive and pragmatic manners [Guimarães et al., 2015]. Contextual Goal Model (CGM) makes explicit presentation of the relationship between a goals and their achievement strategies and the context: “a partial state of the world in which the system operates and is relevant to its goals.” [Ali et al., 2010].

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A Goal Model Example

[p] is no)fied about emergency medical care reaches [p] emergency is detected ambulance is dispatched to [p] loca)on central receives [p] info setup automated [p] info and processes sensors data no)fies [p] by mobile vibra)on

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[p] info is sent to emergency and [p] loca)on is iden)fied access [p] loca)on [l] from triangula)on send [p] info by SMS acess data from database ¬Ct Cm v ¬Ct Mobile Personal Emergency Response Cm Ambulance Dispatchin g System situa)ons are iden)fied iden)fies situa)on no)fies [p] by light alert centrals calls [p] vital signs are monitored and collects data from sensors persists data to database and [p] situa)on data is recovered and iden)fies [p] loca)on [l] by voice call send [p] info by internet ¬Ct respond to emergency

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no)fies [p] by sound alert Ct ^ Cha Ct [p] call for help is accepted receives emergency buDon call no)fy central by SMS no)fy central by Internet confirms emergency by call false alarm is checked accepts emergency and Cha ^ ¬Ct Cha ^ ¬Ct access [p] loca)on [l] from a GPS

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Cm v ¬Ct

• r
• r
• r

[p] is contacted Consider last known loca)on [l] of [p] [p] info is prepared get info from responsible for [p] contact responsible for [p]

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Pa)ent contexts: Ch: Health risk Cm: Mobility issue Ct: Technology aversion Cha: Home assistance Ca: Physical ac)vity ¬Ct v Cha (¬Ct v Cha) Ch v Ca Ch v Ca Cha v ¬Ct Ch

Figure : CGM’s Emergy Response in AAL (adapted from [Guimarães et al., 2015])

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Motivation

Goals and capabilities are core and also shared constituents for both goal modelling and personas making the integration of power between both techniques easier and natural!

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Problem

In traditional GORE, people roles, responsibilities and permissions need to be normalized to fit in a general model. However, in reality people play different roles in different ways! And a case by case basis would add infeasible overhead to the engineers by personalizing the requirements [Sutcliffe et al., 2005].

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A Persona-based Modelling for Contextual Requirements

How can we empower GORE modelling practice with personalization and human-centred design facets? In addition, how to devise a goal achievement sensitive to their actual set of personas?

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Persona Attribute Formalization

We formalize the description of the persona attributes into contextual facts as follows:

1 i is the id of the persona in the population of interest. 2 Ai ∈ {A1, A2,...,An}, where A is a set of attributes as nominal

categorical variables of i.

3 Each attribute Ai may have a corresponding contextual fact Fj, where

i ≤ j.

4 i =

j

• n=1

Fn, the persona i is characterized as the union of Fj contextual facts.

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The Personas Contexts

Context as a predicate formula of and/or combinations of statements and facts [Ali et al., 2010]. Contextual facts in our work map only those relevant and verifiable persona information.

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Structuring the Contextual Facts into Contexts

f1= [p] has diabetes f2= [p] has HBP f3= [p] is cardiac f4= [p] has rheumatoid f5= [p] is prone to falling f6= [p] has

• steoporosis

Ch

f7 = [p] is low critical w1=[p] has degree

• f health status

f8 = [p] is medium critical f9 = [p] is high critical Legend FACT Statement OR AND Imply Support

Figure : Excerpt of the Health Context Structure.

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Formalization of a Persona’s Context Set

Definition (Persona Context Set)

Let the mapping function C: i

Cj

− → {T, F} which returns true or false for the facts of persona i applied to context Cj. If Cj(i) = T, it means that Cj ∈ Ω, where Ω is the set of contexts triggered by persona i.

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A Context Set Example

Based on the Persona Mary Collins attributes and goals, Mary’s context set follows: Facts: (F1,F5,F6,F14,F19) Health Context (Ch): (F1 & F5 & F6) Home Assistance (Cha): (F14) Technology Aversion (Ct): (F19) Therefore, Mary’s Context Set = {Ch, Cha, Ct}

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The Relationship Between Actors and Persona Goals

Persona Goal Actor Goal Actor Persona Goal Persona Goal Persona:P1 Persona:P3 Persona:P2 C1 C2 C3

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Achievability of a Persona Goal Satisfaction

Definition (Persona Goal Satisfaction)

Let the context set Ω triggered by persona i, the actor goal Γ, which the persona goal is link dependent, and the target system CGM. The persona goal satisfaction property Φi is achieved when (Ω, Γ, CGM) Φi

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Goal Achievement Check

Persona goal satisfaction via the goal achievement check algorithm (further details on the paper). CGM goals achievability facing personas context sets. Enables richer adaptation decisions for:

Achievability analysis in explicitly modelled user context The effect of the user context on a goal fulfillment criteria

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Goal Achievement Check

Persona goal satisfaction via the goal achievement check algorithm (further details on the paper). CGM goals achievability facing personas context sets. Enables richer adaptation decisions for:

Achievability analysis in explicitly modelled user context The effect of the user context on a goal fulfillment criteria

The achievability of a goal is a selection and enactment of a suitable alternative to reach a goal under a certain or multiple persona contexts criteria.

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Feasibility Study on MPERS

19 distinctive facts for the considered personas. Eight distinctive contexts: five for the patients and three for the medical doctor. Four modelled personas: 3 patients and 1 doctor

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Feasibility Study on MPERS – The GQM

Table : GQM devised plan Goal: Analysis of the achievability of the goals Question Metric Q1. Is the algorithm efficient to come up with an execution plan? Execution time Q2. Does the algorithm allow testing and explaining persona-based goal achievability? Yes/No Q3. Are the plans provided by the algorithm correct? % of correct plans

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Results

Q1 - Is the algorithm efficient to come up with an execution plan?

Algorithm’s complexity for the goal achievement check is linear on time (further details on the paper).

Q2 - Does the algorithm allow testing and explaining persona-based goal achievability?

Only Mary did not have the MPERS goals achieved! Mary has technology aversion to some degree since she fears having frustrating experiences with technology.

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Results

• Q3. Are the plans provided by the algorithm correct?

Notify central by SMS Notifies [p] by mobile vibration Accepts emergency Send [p] info by SMS Consider last known location [i] of [p] Ambulance Dispatching System Planning 1 Identifies [p] location [i] by voice call Access data from database Planning 2

Figure : Achievable Plans for the provided personas contexts.

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Conclusions and Future Work

Persona-based structuring and impact analysis on goals achievement Alignment between personas intentions and capabilities as context information in a goal oriented perspective. Feasibility studies performed on MPERS. In the future:

Analyse in the presence and perspective of multiple actors Analyse the impact of the personas on NFR analysis

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Acknowledgement

The authors would like to express their gratitude for the fruitful discussions with Shamal Faily, Felipe Pontes, Célia Ralha and Renato Pina during the development of this work. Genaína would like to thank CAPES-PROCAD for the partial financial support of this work.

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References I

Alan Cooper. The Inmates Are Running the Asylum: [Why high-tech products drive us crazy and how to restore the sanity]. Sams Publishing, US, 2004. ISBN 0672326140. Felipe Pontes Guimarães, Genaína Nunes Rodrigues, Daniel Macêdo Batista, and Raian

• Ali. Pragmatic requirements for adaptive systems: A goal-driven modeling and

analysis approach. In ER, volume 9381 of Lecture Notes in Computer Science, pages 50–64. Springer, 2015. Alistair Sutcliffe, Stephen Fickas, and McKay M. Sohlberg. Personal and contextual requirements engineering. 13th IEEE International Conference on Requirements Engineering (RE’05), páginas: 19-28, 2005. Raian Ali, Fabiano Dalpiaz, and Paolo Giorgini. A goal-based framework for contextual requirements modeling and analysis. Requirements Engineering, 15(4):439–458, July

• 2010. ISSN 0947-3602. doi: 10.1007/s00766-010-0110-z.

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